Multiphase Engineered BNT-Based Ceramics with Simultaneous High Polarization and Superior Breakdown Strength for Energy Storage Applications

Dielectric ceramics are crucial for high-temperature, pulse-power energy storage applications. However, the mutual restriction between the polarization and breakdown strength has been a significant challenge. Here, multiphase engineering controlled by the two-step sintering heating rate is adopted to simultaneously obtain a high polarization and breakdown strength in 0.8(0.95Bi(0.5)Na(0.5)TiO(3)-0.05SrZrO(3))-0.2NaNbO(3) (BNTSZNN) ceramic systems. The coexistence of tetragonal (T) and rhombohedral (R) phases benefits the temperature stability of BNTSZNN ceramics. Increasing the heating rate during sintering reduces the diffusion of SrZrO3 and NaNbO3 into Bi0.5Na0.5TiO3, which results in a high proportion of the R phase and a finer grain size. The overall polarization is enhanced by increasing the proportion of the high-polarization R phase, which is demonstrated using a first-principles method. Meanwhile, the finer grain size enhances the breakdown strength. Following this design philosophy, an ultrahigh W dis of 5.55 J/cm(3) and eta above 85% is achieved in BNTSZNN ceramics as prepared with a fast heating rate of 60 degrees C/min given a simultaneously high polarization of 43 mu C/cm(2) and high breakdown strength of 350 kV/cm. Variations in the discharge energy density from room temperature to 160 degrees C are less than 10%. Additionally, such BNTSZNN ceramics exhibit an ultrafast discharge speed with tau(0.9) at approximately 60 ns, which shows great potential in pulse-power system applications.

Automated summary

Multiphase engineering controlled by the two-step sintering heating rate is adopted to achieve high polarization and breakdown strength in BNTSZNN ceramics. The coexistence of tetragonal and rhombohedral phases improves temperature stability. Increasing heating rate reduces diffusion and enhances polarization while finer grain size enhances breakdown strength.